Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$196.56	9.679%	$215.585	$215.59	$215.60	$215.60
Purchase #2	$72.27	5.847%	$76.4956	$76.50	$76.50	$76.50
Purchase #3	$80.67	6.207%	$85.6772	$85.68	$85.70	$85.70
Purchase #4	$191.88	3.316%	$198.2427	$198.24	$198.25	$198.20
Purchase #5	$101.80	3.636%	$105.5014	$105.50	$105.50	$105.50
Purchase #6	$99.28	4.841%	$104.0861	$104.09	$104.10	$104.10
Purchase #7	$89.34	12.330%	$100.3556	$100.36	$100.35	$100.40
7 purchase totals =	$831.80		$885.9436	$885.96	$886.00	$886.00